The present invention relates generally to spacecraft communication systems, and more particularly, to a waveguide slot array antenna system that is capable of radiating shaped beams.
The assignee of the present invention manufactures and deploys communication satellites. Such communication satellites carry communication systems and antennas that are used to communicate with ground-based communication devices. Heretofore, communication systems have employed conventional waveguide slot array designs.
The closest known prior art relating to the present invention is the conventional waveguide slot array. This well-known design radiates in-phase signal contributions from each slot in the array and is therefore restricted to simple circular or elliptical beam shapes.
It would therefore be desirable to have a waveguide slot array that may be advantageously used in a satellite-based communication system and that provides for shaped radiated beam profiles. It is therefore an objective of the present invention to provide for a waveguide slot array antenna system that is capable of radiating shaped beams.
To accomplish the above and other objectives, the present invention comprises an improved waveguide slot array antenna system. The waveguide slot array antenna system may be advantageously used as part of a communications system disposed on a satellite.
The waveguide slot array antenna system comprises a feed waveguide having an input port and multiple output ports. A waveguide slot array having a plurality of slots formed therein is coupled to the feed waveguide. A waveguide lens comprising an array of rectangular waveguides is disposed adjacent to the waveguide slot array. The phase of each radiating waveguide of the waveguide lens is controlled to achieve radiation pattern shaping. This capability has not been achieved by conventional waveguide slot array designs.
Thus, in order to achieve control of the phase radiated from the waveguide slot array antenna system, the array of rectangular waveguides forms a waveguide lens in front of the plurality of radiating slots and is an integral part of the structure of the system. Inner dimensions of the rectangular waveguides are designed to provide a phase velocity inside each waveguide that results in the appropriate radiated phase at the output of the waveguides.
The advantage of using the present waveguide slot array antenna system is that the phase radiated by each rectangular waveguide is determined by design, and the radiation pattern that results from the combined contributions of the array can be shaped to demonstrate a complex radiation contour. This significantly increases the efficiency with which signals are directed to intended regions without coverage directed to unintended regions.